Optical polarization response at gold nanosheet edges probed by scanning near-field optical microscopy

• 来源期刊: 中国物理B（英文版）
• 关键词: nanosheet scanning near-field optical microscopy edge effect depolarization
• 年，卷（期）: 2018,（8）
• 页码范围: 564-568
• 页数: 5页
• 语种: 英文
• DOI: 10.1088/1674-1056/27/8/087801

摘要

Optical properties of metallic edge-like structures known as knife-edges are a topic of interest and possess potential applications in enhanced Raman scattering, optical trapping, etc. In this work, we investigate the near-field optical polar-ization response at the edge of a triangular gold nanosheet, which is synthesized by a wet chemical method. A homemade scanning near-field optical microscope (SNOM) in collection mode is adopted, which is able to accurately locate its probe at the edge during experiments. An uncoated straight fiber probe is used in the SNOM, because it still preserves the prop-erty of light polarization though it has the depolarization to some extent. By comparing near-field intensities at the edge and glass substrate, detected in different polarization directions of incident light, the edge-induced depolarization is found, which is supported by the finite differential time domain (FDTD) simulated results. The depolarized phenomenon in the near-field is similar to that in the far-field.